Engineering Questions with Answers - Multiple Choice Questions

# Machine Dynamics MCQ – Stability of a Two Wheel Vehicle Taking a Turn

1 - Question

Which of the following quantity represent the gear ratio “G” for a 2 wheeler vehicle? (w: wheels, e: engine, R: radius of track, rw: radius of wheels & I: moment of inertia)
a) ωw / ωe
b) ωe / ωw
c) rw/ R
d) Ie/ Iw

Explanation: Gear ratio is defined as the ratio of the angular speed of the initial or driving member of a gear train or equivalent mechanism to that of the final or driven member specifically: the number of engine revolutions per revolution of the rear wheels of an automobile.

2 - Question

Which of the following is correct regarding angle of heel?
a) It is inclination of the vehicle to the vertical for equilibrium
b) It is inclination of the vehicle to the horizontal for equilibrium
c) It is the angle between the axis of gyroscope couple and horizontal
d) It is the angle between the axis of spin couple and axis of precession

Explanation: The axis of spin is inclined to the horizontal at an angle θ, when a two wheel vehicle is taking a turn this is the angle it makes with the vertical plane and it is known as angle of heel.

3 - Question

Which of the following is correct regarding angle of heel?
a) It is the angle between the axis of spin couple and axis of precession
b) It is the angle between the axis of gyroscope couple and horizontal
c) It is inclination of the vehicle to the horizontal for equilibrium
d) It is inclination of the axis of spin to the horizontal for equilibrium

Explanation: While taking a turn, a two wheel vehicle is always at an inclination of an angle θ with the vertical plane. This angle is known as angle of heel and is denoted by theta. In other words, the axis of spin is inclined to the horizontal at an angle θ.

4 - Question

When is the positive sign used for the expression of gyroscopic couple?
a) Centre of gravity is lower than the centre of vehicle
b) When the engine is rotating in the opposite direction as that of wheels
c) When the engine is rotating in the same direction as that of wheels
d) Centre of gravity is higher than vehicle centre

Explanation: To decide the direction of rotation between wheels and the engine, conventionally a positive sign represents the same direction and negative sign represents opposite direction.

5 - Question

The centrifugal couple’s tendency is to overturn the vehicle.
a) True
b) False

Explanation: When a two wheel vehicle is taking a turn, it experiences a centrifugal force acting on it which has a tendency to turn the vehicle upside down about a horizontal plane, whereas as centripetal force would prevent the overturning.

6 - Question

The centrifugal couple affects the stability of a two wheel vehicle taking a turn.
a) True
b) False

Explanation: While taking a turn a two wheel vehicle experiences a centrifugal couple acting on it which has a tendency to turn the vehicle upside down about a horizontal plane. This force has to be balanced by a balancing couple.

7 - Question

Balancing couple is given by _______ (θ: angle of heel)
a) m.g.h cos θ
b) m.g.h sin θ
c) m.g.h
d) (m.v2).h/R

Explanation: The balancing couple required for the stability of the two wheel vehicle taking a turn is the cross product of height of centre of gravity and weight of the vehicle.

8 - Question

Which of the following is true regarding overturning couple?
a) It is the sum of gyroscope couple and centrifugal couple
b) It is the product of gyroscope couple and centrifugal couple
c) It is the difference of gyroscope couple and centrifugal couple
d) It is the ratio of gyroscope couple and centrifugal couple

Explanation: Since the centrifugal couple has a tendency to overturn the vehicle, therefore Total overturning couple Co is given by: Co = Gyroscopic couple + Centrifugal couple.

9 - Question

What is the relation between overturning couple and balancing couple for the stability of vehicle?
a) Independent of each other
b) Overturning couple is greater
c) Balancing couple is greater
d) Equal to each other

Explanation: The balancing couple acts in clockwise direction when seen from the front of the vehicle. Therefore for stability, the overturning couple must be equal to the balancing couple.

10 - Question

In the figure below what is known as the angle “x”? a) Angle of ascent
b) Angle of heel
c) Gyroscope angle
d) Angle of precession